EVM MCP Server

Instructions

Implementation Reference

• src/index.ts:391-430 (handler)

  The complete server.tool registration which defines the handler function for the 'eth_getTransactionReceipt' tool. The handler takes a txHash, calls the RPC method via makeRPCCall, formats the response using formatResponse, and handles errors.

  server.tool(
    "eth_getTransactionReceipt",
    "Returns the receipt of a transaction by transaction hash",
    {
      txHash: z.string().describe("Transaction hash"),
    },
    async ({ txHash }) => {
      try {
        const result = await makeRPCCall("eth_getTransactionReceipt", [txHash]);
        if (!result) {
          return {
            content: [
              {
                type: "text",
                text: `Transaction receipt not found: ${txHash}`,
              },
            ],
          };
        }
  
        return {
          content: [
            {
              type: "text",
              text: formatResponse(result, "Transaction Receipt"),
            },
          ],
        };
      } catch (error: any) {
        return {
          content: [
            {
              type: "text",
              text: `Error: ${error.message}`,
            },
          ],
        };
      }
    },
  );

• src/index.ts:394-396 (schema)

  Input schema for the tool, defining 'txHash' as a required string parameter.

  {
    txHash: z.string().describe("Transaction hash"),
  },

• src/index.ts:89-96 (helper)

  Shared helper function makeRPCCall used by the eth_getTransactionReceipt handler to perform the actual RPC call to the Ethereum provider.

  async function makeRPCCall(method: string, params: any[] = []): Promise<any> {
    try {
      const result = await provider.send(method, params);
      return result;
    } catch (error: any) {
      throw new Error(`RPC call failed: ${error.message}`);
    }
  }

• src/index.ts:32-86 (helper)

  Shared helper function formatResponse used to format the tool output in markdown.

  function formatResponse(data: any, title: string): string {
    let result = `**${title}**\n\n`;
  
    if (typeof data === "object" && data !== null) {
      if (Array.isArray(data)) {
        // Handle arrays
        result += `**Count:** ${data.length}\n\n`;
        data.forEach((item, index) => {
          result += `**${index + 1}.**\n`;
          if (typeof item === "object" && item !== null) {
            result += formatObject(item, "  ");
          } else {
            result += `  ${item}\n`;
          }
          result += "\n";
        });
      } else {
        // Handle objects
        result += formatObject(data, "");
      }
    } else {
      result += `${data}\n`;
    }
  
    return result;
  }
  
  // Helper function to format objects recursively
  function formatObject(obj: any, indent: string): string {
    let result = "";
  
    for (const [key, value] of Object.entries(obj)) {
      if (typeof value === "object" && value !== null) {
        if (Array.isArray(value)) {
          result += `${indent}**${key}:** [${value.length} items]\n`;
          if (value.length > 0 && value.length <= 10) {
            value.forEach((item, index) => {
              if (typeof item === "object" && item !== null) {
                result += `${indent}  ${index}: ${JSON.stringify(item, null, 2).replace(/\n/g, "\n" + indent + "    ")}\n`;
              } else {
                result += `${indent}  ${index}: ${item}\n`;
              }
            });
          }
        } else {
          result += `${indent}**${key}:**\n`;
          result += formatObject(value, indent + "  ");
        }
      } else {
        result += `${indent}**${key}:** ${value}\n`;
      }
    }
  
    return result;
  }